Australia skipper Michael Clarke has become the first batsman to hit four test double centuries in a calendar year.

Clarke took a single against Imran Tahir to reach 200 late on the opening day of the second test against South Africa, his second double century in consescutive
innings after his unbeaten 259 in the drawn first test last week in Brisbane.

He went to the crease with Australia in trouble at 55-3 on Thursday and stroked 35 boundaries and a six to reach 200 from 226 balls.

The 31-year-old Clarke started the year with 329 not out at Sydney and 210 at Adelaide in January against India. The great Donald Bradman scored three double centuries in an Ashes series in England in 1930.